Mercury (Hg) content behaviour was followed along the canning process in muscle samples of tuna fish to point out implications concerning canned tuna consumers. Hg was quantified in the same batch of the Skipjack tuna (Katsuwonus pelamis), considering three distinct stages (raw, cooked and canned tuna) independently in both white and dark muscle tissue. Hg concentration data was then used to estimate the weekly tolerable intake of Hg regarding the recommendations from the international agencies. A small but significant difference in Hg concentration between white and dark muscle was observed either in the raw samples (0.115 +/- 0.003 mu g g(-1) against 0.124 +/- 0.003 mu g g(-1)) as also in the canned samples (0.134 +/- 0.003 mu g g(-1) against 0.155 +/- 0.003 mu g g(-1)). Overall results indicate an increment in the Hg concentration in both types of muscle throughout the canning process (raw < cooked < canned), although being only statistically significant between raw and canned samples. However, regarding the limits imposed by international agencies, the consumption of the examined canned products, do not represent a risk in terms of human diet. (C) 2016 Elsevier Inc. All rights reserved.

This work was supported by the Portuguese Science Foundation (FCT) through CESAM: UID/AMB/50017/2013. FCT also financed a post-doctoral research grant to M. D. Bordalo (SFRH/BPD/94494/ 2013). The authors would like to thank the contribution of Empresa de Pesca de Aveiro (EPA) to this work by guidance along the tuna canning process and authorizing the sampling in its facilities.